Biochemistry, Genetics, and X-ray crystallography of Vitreoscill

Biochemistry, Genetics, and X-ray crystallography of Vitreoscilla Cytochrome bo Quinol Oxidase

- 일 시 : 2001년 6월 5일(화) 16:00-17:00

- 연 사 : Kyung-Jin Kim Ph.D.


           (Industrial Macromolecular Crystallography


            Association Collaborative Access Team (IMCA-CAT),


            Advanced Photon Source, Argonne National Laboratory


            and Illinois Institute of Technology)

- 장 소 : 생명관 104호 세미나실


- 문의처 : 오병하 교수 (279-2289)

- Abstract


Vitreoscilla is a Na+ motive organism, generating a Na+ electrochemicalgradient during term nal respiration. The cytochrome bo ubiquinol oxidaseof this organism was identified as a primary Na+ pump. This oxidase hasfive subunits (CyoA-E) whose topological analysis shows that all of thesubunits are membrane-bound except 24 kDa soluble domain at the C-terminalend of CyoA (subunit II). The sodium pumping function of Vitreoscillacytochrome bo was proved using cyo(-) knockout mutant, and further provedby the experiment using cytochrome bo containing proteoliposomes, whichtranslocate Na+ when energized with ubiquinol. Complementation experimentof Na+-transport-lacking-mutant showed that CyoB (subunit I) is playing amajor role in Na+ pumping. The crystal structure of 24 kDa CyoA solubledomain, a putative quinol binding domain, was solved, and compared withthat of E. coli. Overall CyoA soluble domain structures from these twoorganisms are similar except for some differences around the putativequinol binding site, postulating structural difference between H+ pumpingand Na+ pumping CyoA soluble domains.